Acid-base properties of γ-Al 2O 3 and MgO-Al 2O 3 supported gold nanoparticles

Abstract

Gold nanoparticles supported on γ-alumina and magnesia-doped γ-alumina were synthesized by co-precipitation via a modified sol-gel method. The syntheses were found to produce catalysts with controllable acidity; the presence of either gold or magnesia produced catalyst possessing unbalanced density of acidic and basic sites, while the addition of both gold and magnesia produced catalyst possessing balanced density of relatively stronger acidic and basic sites. The variation of the acid-base strengths of the synthesized catalysts was assessed by using NH 3-TPD, CO 2-TPD, and infrared analysis of adsorbed CO 2 and correlated to their catalytic activity in 2-propanol decomposition probe reaction. Catalysts containing magnesia and gold were found to exhibit base catalytic properties through their greater selectivity for acetone formation, while plane γ-alumina and γ-alumina doped with magnesia or gold exhibited acid catalytic properties through their selectivity for propene formation. © 2012 Elsevier B.V.